Brown said Thursday night he had promised to work for the middle class and has done so with such actions as supporting the auto industry bailout.

Mandel has said he opposed the bailout; he says Brown is an example of why Washington isn't working.

In Columbus last week, Mandel looked into the camera and flatly called Brown "a liar," responding to a Brown campaign theme that Mandel can't be trusted.

Brown said that was "a pretty remarkable thing" for Mandel to say, calling the Republican the winner of "pants on fire" ratings in the fact-checking column of The Plain Dealer newspaper.

Mandel has depicted the 59-year-old veteran Democrat as a career Washington politician who uses "Washingtonspeak," while Brown has described his 35-year-old challenger as opportunistic and more concerned about his next office than doing the job he has.

They have split on the auto industry bailout backed by President Barack Obama's administration. Brown supported it and says it has saved thousands of Ohio jobs in auto-making plants and auto-related businesses.

Mandel said recently he opposed the bailout as unfair and fiscally irresponsible. The Obama campaign has been hammering Republican challenger Mitt Romney on the auto issue this week, in advertising and during rallies in Ohio. The state is considered pivotal in the presidential race, and also draws strong interest for the Senate race.

Republicans identified Brown, who unseated Mike DeWine in the 2006 election, as an early target in their bid to win control of the Senate, but polls have indicated Brown has been able to hang onto the lead in their race. It has drawn heavy outside ad spending on top of the some $30 million in spending by the two campaigns combined.

Mandel is a Marine veteran of Iraq who was a Cleveland-area city councilman and state legislator before being elected state treasurer two years ago.

Brown is a former Ohio secretary of state and state legislator elected to the U.S. House in 1992. Brown has championed the Obama health care overhaul, which Mandel calls "government-run health care" that he opposes. Brown supports abortion rights and gay marriage, both also opposed by Mandel.

Brown and Mandel have focused on their differences on issues from abortion to the auto industry bailout in the last debate of Ohio's heated race.

Brown describes himself as a fighter for the middle class and steadfast supporter of women's choice on abortion.

Mandel says he would help economic growth with lower taxes and seek "common ground" on the divisive issue of abortion. He says he opposes abortion except to save a woman's life.

Their exchanges Thursday night weren't as vitriolic as their second debate last week, although peppered with sarcasm.

Mandel gave a somewhat conciliatory closing, praising Brown's wife and his own.

Brown thanked him in their debate televised around the state on NBC affiliates.

Hundreds of raucous supporters on both sides waved signs and chanted outside.